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At least 829 records · Page 46Linked to original sources
PubMed1986

Sedimentation volume, redispersibility and appearance of a polystyrene latex suspension in the presence of nonionic surface active agents.

The sedimentation volume, redispersibility and appearance of a polystyrene latex suspension in the presence of nonionic surface active agent of polyoxyethylene glycol monoethers of n-hexadecanol have been investigated. At low concentrations of nonionic surface agents, hard caked suspensions were found. This is probably due to the attraction between the uncoated areas or the mutual adsorption of the adsorbed molecules on the bare surface of the particles in the sediment. At high concentrations of nonionic surface active agents, the redispersibility of the particles was affected by the steric repulsive force.

Cetomacrogol↗
PubMed1987

Deposition and clearance of radiolabelled monodisperse polystyrene spheres in the calf lung.

Two groups of three calves were exposed to monodisperse aerosols of radiolabelled polystyrene spheres measuring 3.3 microns in aerodynamic diameter (SD 0.3 micron). Although the spheres preferentially deposited in the trachea and major bronchi, 72 per cent of the total radioactivity deposited was found in lung tissue beyond the major bronchi. Mean alveolar deposition, estimated from the end retention value after mucociliary clearance, was 34 per cent in the group of bull calves and 52 per cent in the group of heifer calves. Alveolar deposition increased from 47 to 56 per cent (P less than 0.05) in heifer calves treated with oestradiol. Mucociliary clearance of the spheres was unaffected by repeated exposure to the experimental aerosol and the overall mean mucociliary clearance rate constant was 1.28 (+/- 0.43) h-1 (half-life 32 minutes). Clearance curve profiles tended to be characteristic for individual calves but variation in mucociliary clearance rates within calves was high and on occasions clearance rate inexplicably fell to 10 to 50 per cent of the maximum achievable value for the calf. Neither mucociliary clearance rate nor alveolar deposition was affected by a change in climate from 14 degrees C, 87 per cent relative humidity to 5 degrees C, 75 per cent relative humidity. Both alveolar deposition and mucociliary clearance of the spheres could be manipulated using a beta-adrenergic treatment.

Aerosols↗
PubMed1987

Intestinal necrosis due to sodium polystyrene (Kayexalate) in sorbitol enemas: clinical and experimental support for the hypothesis.

Five patients who suffered catastrophic colonic necrosis are presented. All patients were uremic and received sodium polystyrene (Kayexalate) in sorbitol enemas for the treatment of hyperkalemia shortly before the development of signs and symptoms of colonic necrosis. In all specimens extensive ischemic necrosis was present, and Kayexalate crystals were noted in the intestinal lumen. Four of the five patients eventually died. To further investigate the occurrence of colonic necrosis after the administration of Kayexalate in sorbitol enemas, a series of experiments were performed in rats. Two groups of Sprague-Dawley rats were studied. One group was made uremic by performance of bilateral nephrectomy. The other group underwent sham operation. Enemas of saline, Kayexalate alone, sorbitol alone, or Kayexalate in sorbitol were administered. In nonuremic rats, transmural necrosis was noted in seven of 10 rats receiving sorbitol enemas and in six of 10 rats receiving Kayexalate in sorbitol enemas. No significant pathologic changes were noted in the rats receiving other enemas. In uremic rats, extensive transmural necrosis was noted in all rats receiving enemas of sorbitol or Kayexalate in sorbitol. All of these 19 rats died within the period of observation compared with no deaths in 18 rats that received enemas without sorbitol (p less than 0.001).

Adolescent↗
PubMed1985

Quantitative localization of polystyrene microspheres following microinjection in the avian metencephalic neural crest pathway.

Polystyrene microspheres were microinjected into crest populations at two preotic sites in Hamburger-Hamilton stage 10 and 11 chick embryos to investigate factors modulating cephalic neural crest fate. Analyses of microsphere localization and comparisons with cephalic crest fate maps indicated the following: microspheres injected at stage 10 localized with derivatives reflecting the fate of the crest population at the injection site; microspheres injected at stage 11 exhibited minimal displacement; and localization in ectoderm was similar in embryos injected at either stage. These results suggest that microinjected microspheres can be used to investigate normal and abnormal craniofacial morphogenesis.

Animals↗
PubMed1984

Toxicity of the components of styrene polymers: polystyrene, acrylonitrile-butadiene-styrene (ABS) and styrene-butadiene-rubber (SBR). Reactants and additives.

The toxicity of the components of styrene polymers, e.g., polystyrene, ABS and SBR, were reviewed with primary focus on the reactive monomers (except styrene) (e.g., acrylonitrile, butadiene) as well as on impurities and solvents such as benzene, hexane and methylethyl ketone, and additives such as phenyl-2-naphthylamine, di-n-butyl phthalate, and a number of peroxide initiators and flame retardants (e.g., 2,3-dibromopropanol, decadibromodiphenyl oxide and antimony trioxide). It is stressed that toxicity data are generally lacking for the majority of additives employed in the production of styrene polymers. Information is also lacking as to the numbers of individuals at potential risk and the extent of their exposure to the large number of additives employed.

1-Naphthylamine↗
PubMed1984

[Fixation of antibodies by covalent bonds to polystyrene: use of the immunoenzyme technic for the detection of Escherichia coli K99 in calf feces].

A solid phase enzyme immunoassay using antibodies covalently bound to polystyrene balls is developed. Results show the same sensitivity as the method with antibodies adsorbed to solid support. By means of K99+ E. coli detection on diarrhoeic calves, results are compared with bacteriological findings. The interest of the method is discussed.

Animals↗
PubMed1984

Direct depletion and purification of monoclonal antibody defined cells from unfractionated human mononuclear leukocytes using antibody coated polystyrene Petri dishes.

Human peripheral blood mononuclear leukocytes were depleted or enriched in various monoclonal antibody-defined subsets using a simplification of the indirect " panning " technique. Unfractionated mononuclear leukocytes (MNL) were sensitized with appropriate dilutions of monoclonal antibodies to human Lyt3 , OKT4 and OKT8 antigens, and to a monocyte-myeloid line antigen. The sensitized cells were then placed on polystyrene Petri dishes coated with goat antimouse IgG to obtain a population of cells depleted and a population of cells enriched in each cell type. Direct separation of surface immunoglobulin-bearing cells was similarly achieved by coating the Petri dish with goat antihuman immunoglobulins. Results showed that MNL could be depleted to greater than 95% purity with these methods and that positively selected adherent cells could be enriched to at least 85% purity. The relative proportions of MNL subpopulations in various sorted cell populations is reported. Cells obtained by panning are functionally intact. As compared to complement lysis both marker positive and marker negative cells can be obtained and the technique requires less technical expertise than using fluorescence activated cell sorting. The modification reported here is simpler and less time consuming for human T cell subpopulation separations than previously reported panning methods since an initial sheep erythrocyte rosetting step was not used.

Animals↗
PubMed1978

Thermal degradation products of homopolymer polystyrene in air.

Polystyrene without additional compounds was treated in a laboratory oven at elevated temperatures (200 degrees, 350 degrees, 500 degrees C) under slight air flow (0.7 l/min). The thermal degradation products appearing in different phases (gases, vapors, aerosols) were collected and analyzed by methods of chromatography. Thermogravimetric analysis showed the thermal degradation of the polymer to begin at 270 degrees C in air and stop at 425 degrees C. The main groups of vaporized compounds generated were monoalkyl-substituted aromatic hydrocarbons and their oxidized products, of which styrene monomer and benzaldehyde were the most abundant. Only trace amounts of carbon monoxide and aliphatic compounds (hydrocarbons, aldehydes, and acids) were produced. The aerosol produced, the amount of which increased as the temperature rose, contained mainly fragments of the polymer chain (e.g., dimers and trimers of styrene). The traces of styrene, cumene, and ethylbenzene that appeared at 200 degrees could represent residual compounds in the initial polymer and indicate the beginning of the thermal degradation. If proportional concentrations are kept as a criterion, the important products, from the point of view of industrial hygiene, were styrene, benzaldehyde, styrene oxide, acetophenone, and l-phenylethanol. The large amount of aerosol that appeared may also be of practical importance.

Acids↗
PubMed1978

Health status of styrene-polystyrene polymerization workers.

Styrene monomer is a greatly used chemical, chiefly in the production of polystyrene. A cross-sectional health survey of 493 production workers was undertaken at the oldest and largest monomer production, polymerization, and extrusion facility in the United States. Relative exposure durations and levels were obtained from occupational histories and corroborated by spot air sampling, blood and fat styrene concentrations and levels of urinary mandelic and phenylglyoxylic acids. Statistically significant differences between the prevalence of abnormalities in high and low exposure groups were found for the following: history of acute prenarcotic symptoms, history of acute lower respiratory symptoms, peroneal nerve conduction velocities, relative lymphocytosis, and elevated gamma glutamyl transpetsidase. The following showed no distinct pattern in prevalence when analyzed by exposure group: chest radiographic changes; indices or restrictive, obstructive and small airway dysfunction; other hepatic and hematological parameters; carcinoembryonic antigen level; sputum cytopathology; radial nerve conduction velocities; and ophthalmological findings. Clinically significant abnormalities were rare.

Environmental Exposure↗
PubMed1978

Mortality experience of styrene-polystyrene polymerization workers. Initial findings.

A group of 560 individuals has been identified as employed on 1 May 1960 with at least five years seniority in a plant manufacturing styrene and polystyrene. In this plant workplace exposures included styrene, benzene and ethylbenzene, among other materials. All of the 560 individuals have been traced through 1975 and their vital status determined. Expected and observed deaths, by cause, were determined from 1 May 1960 or the tenth anniversary of employment in the plant through 31 December 1975. Over this relatively short period of time a deficit of deaths compared to that of the general population was observed (106.41 expected versus 83 observed). Among the 83 deaths, one was of leukemia, one of lymphoma and an additional death was accompanied by leukemia. A review of 361 additional death certificates revealed five additional cases of leukemia and four of lymphoma. The available information from the limited follow-up in time of the time of the cohort and from the randomly collected death certificates, while suggestive of a possible risk, is not definitive.

Adult↗
PubMed1978

Effects of thermal degradation products of polystyrene on drug biotransformation and tissue glutathione in rat and mouse.

Rats and mice were exposed to the fumes of oxidative thermal degradation of polystyrene (350 degrees C). A decrease in the reduced glutathione (GSH) in both liver and lung was detected immediately after both the acute (mice, 3 h) and subacute (rats, 3 weeks) exposures were stopped. Later on an elevation in the amount of GSH due to the increased synthesis (rebound effect) could be seen. Cytochrome P-450 content in mouse liver was initially decreased after acute exposure, but the prolonged treatment doubled the amount of the P-450 hemoprotein in liver microsomes. After acute exposure 7-ethoxycoumarin 9-deethylase activity in mouse liver was doubled in 24 h. When the exposures were continued, this enhancement in ethoxycoumarin O-deethylase activity gradually disappeared. O-deethylase activity was also enhanced in rat liver and lung after subacute exposure. The exposures given had no effect on diphenyloxazole hydroxylase, and the effects on the conjugating enzymes (epoxide hydratase, UDPglucuronosyltransferase, glutathione S-transferase)) were insignificant in rat liver.

Animals↗
PubMed1978

The effect of radiolabeling of human fibrinogen on its adsorption behaviour on a polystyrene surface.

Human fibrinogen (HFB) was labeled with different radioactive labels (Technetium -99m and iodine -125) in various ways. Characterization by chromatographic and electrophoretic methods did not show differences between the labeled and the nonlabeled proteins. The effect of the label and the labeling method on the adsorption behaviour of 99mTc and 125I labeled HFB at a polystyrene surface was investigated. In all cases labeled HFB showed preferential adsorption as compared to nonlabeled HFB. The preferential adsorption was expressed in terms of a factor ø (van der Scheer et al. 1978a), which will be 1, when no preferential adsorption occurs. 99mTc - and 125I - HFB showed ø values from 1.48 - 1.88. It is concluded that only meaningful adsorption experiments with labeled proteins can be performed when the possible occurrence of preferential adsorption has been investigated by appropriate methods. The results of prior work on protein adsorption at biomaterials using radiolabeled proteins have to be reconsidered.

Adsorption↗
PubMed1994

Effect of pretreatment of wells in polystyrene plates on adsorption of some human serum proteins.

Coating of Immulon polystyrene plates with 0.2% casein in phosphate buffered saline (PBS) completely abolishes adsorption of human serum proteins to these plates. However, pretreatment of such plates with PBS or 0.15 M NaCl in deionized water (10 microS) before coating makes possible adsorption of human immunoglobulins G (HIgG) and M but not serum albumin (HSA) and transferrin (HTrf). Effect of pretreatment with PBS on adsorption of HIgG is long-term and rather stable. Results of experiments with radioiodinated HIgG, mouse IgG, HSA and human chorionic gonadotropin confirm the peculiar effect of pretreatment with PBS on casein coating. Pretreatment with deionized water, instead of PBS, markedly diminish adsorption but tap or commercial spring waters (> 1000 microS), even without 0.15 M NaCl, affect adsorption similarly to PBS in deionized water. Super pure water (0.05 microS) even with NaCl used for pretreatment does not influence adsorption of HIgG to plates coated with casein. Distinct differences in adsorption of HIgG and HTrf was demonstrated using solutions for ELISA prepared from super pure, deionized and tap waters.

Adsorption↗
PubMed1993

Scanning electron microscopy of the myosin-coated surface of polystyrene beads in a force-movement assay system for ATP-dependent actin-myosin sliding.

We examined the myosin-coated surface of polystyrene beads, which slide on actin filaments in the presence of ATP with characteristics essentially similar to those of contracting muscle, using a high-resolution scanning electron microscope (JSM-890, JEOL). The bead surface was mostly covered with myosin filaments (diameter, 15-45 nm) with helically arranged myosin heads. Considering the amount of force generated by the myosin heads on the bead (approximately 10 pN), this result indicates that the bead movement may be caused by about 10 myosin heads within a short myosin filament segment, but not by randomly oriented myosin heads.

Actins↗
PubMedDate not supplied

Rapid and quantitative assay system for measuring anti-infectious bursal disease virus antibody using monoclonal antibody bound to polystyrene latex microspheres.

A monoclonal antibody (MAb) to infectious bursal disease virus (IBDV) that has virus-neutralizing activity was bound to polystyrene latex microspheres The microspheres agglutinated with extracts of bursae from chickens infected with IBDV. Agglutination was inhibited in a competitive manner by adding serum obtained from IBDV-infected chickens. The level of agglutination-inhibition depended on the serum antibody titer against IBDV. The reaction was visually accomplished within 5 minutes. The titer of this rapid assay showed a close relationship with that of the virus-neutralization test.

Animals↗
PubMedDate not supplied

[Determination of the optimal condition of hemoprotein immobilization on the polystyrene surface].

The effect of pH, buffer composition, salts concentration and protein content on the immobilization efficiency of peroxidase, hemoglobin and their conjugates with bovine serum albumin (BSA) have been studied. All the substances were immobilized on the surface of polystyrene matrix. When using the 0.01 M carbonate-bicarbonate buffer (pH 9.6) immobilization of soluble substances is optimal. It was shown that the sorption efficiency of hemoproteins and their conjugates with BSA is considerably enhanced by drying solution containing ammonium bicarbonate. The increase of ammonium bicarbonate concentration from 0.13 M to 0.5 M leads to the process intensification.

Adsorption↗
PubMedDate not supplied

Optimized preparation of deca(L-alanyl)-L-valinamide by 9-fluorenylmethyloxycarbonyl (Fmoc) solid-phase synthesis on polyethylene glycol-polystyrene (PEG-PS) graft supports, with 1,8-diazobicyclo [5.4.0]-undec-7-ene (DBU) deprotection.

Deca(L-alanyl)-L-valinamide is known to be a challenging model target for solidphase peptide synthesis, due to its hydrophobicity and its tendency to form secondary structures which inhibit acylation and deprotection. Here we report systematic studies on the synthesis of this peptide on an automated continuous-flow instrument, using the 9-fluorenylmethyloxycarbonyl (Fmoc) group for N alpha-amino protection and a polyethylene-glycol polystyrene (PEGPS) graft support. The optimal deprotection reagent proved to be DBU-piperidine-DMF (1:1:48, vol/vol/vol). The synthetic peptides were analyzed and characterized by high-performance liquid chromatography and several mass spectrometric techniques.

Bridged Bicyclo Compounds, Heterocyclic↗